No you don’t. There’s actually a lot of research showing that native English speakers don’t read letters, they read word shapes. And people who read fastest read in even larger groups of words, to the point of eliding segments of sentences or paragraphs entirely.
Chunking is incredibly important for reading speed, and reading hiragana is much closer to reading letters than words. My reading speed in Japanese is nowhere near native, but the way I’ve gained speed so far is almost exclusively by increasing my minimum comprehension unit: I see word patterns, common grammatical constructions, etc., and I don’t need to read them.
> native English speakers don’t read letters, they read word shapes.
Don't try to teach children to read this way, though: it's a high-level technique that comes with practice and familiarity, with near-instant fallback to lower-level techniques as appropriate, or the resort of dyslexics who cannot read any other way. Teaching children to use the approaches used by struggling readers will tend to produce more struggling readers than necessary.
Chunking is incredibly important for reading speed, and reading hiragana is much closer to reading letters than words. My reading speed in Japanese is nowhere near native, but the way I’ve gained speed so far is almost exclusively by increasing my minimum comprehension unit: I see word patterns, common grammatical constructions, etc., and I don’t need to read them.